Numerical Simulation of Blocking and Abnormal Weater in General Circulation

大气环流阻塞及异常天气的数值模拟

• 批准号: 09640518
• 负责人: TANAKA Hiroshi L.
• 金额: $ 1.66万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640518/
• 关键词: Blocking; Abnormal Weather; Barotropic model; Energetics; Baroclinic Instability; Synoptic Waves; General Circulation; Rossby Wave Breaking; 大気大循環; 数値実験; プラネタリー波; ブロッキング高気圧; 長期予報; 2次元乱流; 逆カスケード; 長周期変動; カオス

Abnormal weather in the atmosphere is closely related to tlie occurrence of block-ing high. Understanding of blocking is thus important for the study of extended-range forecasting. In this study, a series of numerical simulations of blocking is conducted using a simple barotropic model which implements a wavemaker as a parametarization of baroclinic instability. It is shown that the model successfuly simulates the life-cycle of blocking.In the model atmosphere, the synoptic disturbances are amplified exponentially by the wavemaker. The exponential growth soon saturates with nonlinear scattering of energy from synoptic to planetary waves associated with a Rossby wave breaking. The analysis of potential vorteity (PV) indisates that the onset of blocking in brought by the Rossby wave breaking. The overturning of high and low PVs tends to oeeur at the topographic stationary ridge.Once a block is formed by the Rossby wave breaking. subsequent. Ross by waves are blocked by it and undergo meridional stretch. The stretched wave then breaks down. depositing fresh low PV at the north and high PV at the south of the blocking system to maintain the block. The result is consistent with the so-called eddy straining mechanism. It is suggested from the result that the expouential growth of synoptic disturbances is esscetial both for the onset and the maintenance of blocking.

大气中的异常天气与阻塞高压的发生密切相关。因此，对阻塞的理解对于长期预报的研究很重要。在这项研究中，一系列的数值模拟阻塞进行了使用一个简单的正压模式，实现了造波机作为一个副金属化的斜压不稳定。结果表明，模式成功地模拟了阻塞的生命周期，在模式大气中，天气扰动被造波器指数放大。指数增长很快饱和与非线性散射的能量从天气到行星波与Rossby波破碎。位涡分析表明，阻塞的发生是由Rossby波的破碎引起的。当Rossby波破碎形成块体时，高、低PV的翻转倾向于在地形静止脊处汇合。随后。罗斯被波浪阻挡，并受到波浪的拉伸。然后，拉伸的波就分解了。在阻塞系统的北部沉积新的低PV，在阻塞系统的南部沉积高PV，以维持阻塞。这一结果与所谓的涡流应变机制是一致的。结果表明，天气扰动的指数增长是阻塞发生和维持的必要条件。

项目成果

Hayasaki, M.and H.L.Tanaka: "A study of drastic warming in the troposphere : A case for the winter of 1989 in Alaska (in Japanese)" Tenki. 46. 123-135 (1999)

Hayasaki, M. 和 H.L.Tanaka：“对流层急剧变暖的研究：1989 年阿拉斯加冬季的案例（日语）”Tenki。

早崎将光、田中博: "対流圏における急激な温度上昇に関する研究:1989年冬季アラスカの事例解析" 天気. in press. (1999)

Masamitsu Hayasaki、Hiroshi Tanaka：“对流层温度快速上升的研究：1989 年阿拉斯加冬季的案例分析”（1999 年出版）。

Tanaka,H.L. and Kazuo Kimura: "Time series analysis of natural variability in barotropic energy of the atmosphere with ECMWF global analysis." J.Meteor.Soc.Japan,(Accepted).(1998)

田中，H.L.

Tanaka,H.L. and A.Hasegawa: "Comparative energetics analysis of climate models with high and low reoslutions. ACCESSING CLIMATE CHANGE : RESULTS FROM THE MODEL EVALUATION CONSORTIUM FOR CLIMATE ASSESSMENT. Chap.4," Gordon and Breach Science Publishers, 41

田中，H.L.

Tanaka,H.L. and Mayumi Arai: "A study of baroclinic-barotropic instability in the Martian atmosphere using a 3-D normal mode expansion." Earth,Planet and Space. (accepted). (1999)

田中，H.L.